[RFC Weston 01/10] protocol: add sub-surfaces

Pekka Paalanen ppaalanen at gmail.com
Fri Feb 22 07:07:45 PST 2013


Add protocol for sub-surfaces, wl_subcompositor as the global interface,
and wl_subsurface as the per-surface interface extension.

Changes in v2:

- Rewrite wl_subcompositor.get_subsurface description, and move mapping
  and commit details into wl_subsurface description. Check the wording
  in wl_subsurface.set_position description.

- Add wl_subsurface.set_commit_mode request, and document it, with the
  commit_mode enum. Add bad_value error code for wl_subsurface.

- Moved the protocol into Weston repository so we can land it upstream
  sooner for public exposure. It is to be moved into Wayland core later.

- Add destroy requests to both wl_subcompositor and wl_subsurface, and
  document them. Experience has showed, that interfaces should always
  have a destructor unless there is a good and future-proof reason to not
  have it.

Signed-off-by: Pekka Paalanen <ppaalanen at gmail.com>
---
 clients/.gitignore      |   2 +
 clients/Makefile.am     |   4 +
 clients/window.h        |   1 +
 protocol/subsurface.xml | 214 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/.gitignore          |   3 +
 src/Makefile.am         |   4 +
 src/compositor.h        |   1 +
 tests/.gitignore        |   2 +
 tests/Makefile.am       |   4 +
 9 files changed, 235 insertions(+)
 create mode 100644 protocol/subsurface.xml

diff --git a/clients/.gitignore b/clients/.gitignore
index dcd4564..16088e8 100644
--- a/clients/.gitignore
+++ b/clients/.gitignore
@@ -20,6 +20,8 @@ simple-egl
 simple-shm
 simple-touch
 smoke
+subsurface-client-protocol.h
+subsurface-protocol.c
 tablet-shell-client-protocol.h
 tablet-shell-protocol.c
 text-client-protocol.h
diff --git a/clients/Makefile.am b/clients/Makefile.am
index 8c9bcd4..5f83acd 100644
--- a/clients/Makefile.am
+++ b/clients/Makefile.am
@@ -81,6 +81,8 @@ libtoytoolkit_la_SOURCES =			\
 	window.h				\
 	text-cursor-position-protocol.c		\
 	text-cursor-position-client-protocol.h	\
+	subsurface-protocol.c			\
+	subsurface-client-protocol.h		\
 	workspaces-protocol.c			\
 	workspaces-client-protocol.h
 
@@ -185,6 +187,8 @@ BUILT_SOURCES =					\
 	desktop-shell-protocol.c		\
 	tablet-shell-client-protocol.h		\
 	tablet-shell-protocol.c			\
+	subsurface-client-protocol.h		\
+	subsurface-protocol.c			\
 	workspaces-client-protocol.h		\
 	workspaces-protocol.c
 
diff --git a/clients/window.h b/clients/window.h
index c2946d8..815b3f1 100644
--- a/clients/window.h
+++ b/clients/window.h
@@ -27,6 +27,7 @@
 #include <wayland-client.h>
 #include <cairo.h>
 #include "../shared/config-parser.h"
+#include "subsurface-client-protocol.h"
 
 #define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
 
diff --git a/protocol/subsurface.xml b/protocol/subsurface.xml
new file mode 100644
index 0000000..1d148d9
--- /dev/null
+++ b/protocol/subsurface.xml
@@ -0,0 +1,214 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="subsurface">
+
+  <copyright>
+    Copyright © 2012-2013 Collabora, Ltd.
+
+    Permission to use, copy, modify, distribute, and sell this
+    software and its documentation for any purpose is hereby granted
+    without fee, provided that the above copyright notice appear in
+    all copies and that both that copyright notice and this permission
+    notice appear in supporting documentation, and that the name of
+    the copyright holders not be used in advertising or publicity
+    pertaining to distribution of the software without specific,
+    written prior permission.  The copyright holders make no
+    representations about the suitability of this software for any
+    purpose.  It is provided "as is" without express or implied
+    warranty.
+
+    THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+    SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+    FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+    SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+    AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+    ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+    THIS SOFTWARE.
+  </copyright>
+
+  <interface name="wl_subcompositor" version="1">
+    <description summary="sub-surface compositing">
+      The global interface exposing sub-surface compositing capabilities.
+      A wl_surface, that has sub-surfaces associated, is called the
+      parent surface. Sub-surfaces cannot be nested.
+
+      A parent surface with its sub-surfaces forms a (compound) window.
+      For window management purposes, this set of wl_surface objects is
+      to be considered as a single window, and it should also behave as
+      such.
+
+      The aim of sub-surfaces is to offload some of the compositing work
+      within a window from clients to the compositor. A prime example is
+      a video player with decorations and video in separate wl_surface
+      objects. This should allow the compositor to pass YUV video buffer
+      processing to dedicated overlay hardware when possible.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="unbind from the subcompositor interface">
+	Informs the server that the client will not be using this
+	protocol object anymore. This does not affect any other
+	objects, wl_subsurface objects included.
+      </description>
+    </request>
+
+    <enum name="error">
+      <entry name="bad_surface" value="0"
+             summary="the to-be sub-surface is invalid"/>
+      <entry name="bad_parent" value="1"
+             summary="the given parent is a sub-surface"/>
+    </enum>
+
+    <request name="get_subsurface">
+      <description summary="give a surface the role sub-surface">
+	Create a sub-surface interface for the given surface, and
+	associate it with the given parent surface. This turns a
+	plain wl_surface into a sub-surface.
+
+	The parent surface must not be a sub-surface itself.
+	The to-be sub-surface must not already have a dedicated
+	purpose, like any shell surface type, cursor image, drag icon,
+	or sub-surface. It also must not be a parent to further
+	sub-surfaces. Otherwise a protocol error is raised.
+      </description>
+
+      <arg name="id" type="new_id" interface="wl_subsurface"
+           summary="the new subsurface object id"/>
+      <arg name="surface" type="object" interface="wl_surface"
+           summary="the surface to be turned into a sub-surface"/>
+      <arg name="parent" type="object" interface="wl_surface"
+           summary="the parent surface"/>
+    </request>
+  </interface>
+
+  <interface name="wl_subsurface" version="1">
+    <description summary="sub-surface interface to a wl_surface">
+      An additional interface to a wl_surface object, which has been
+      made a sub-surface. A sub-surface has one parent surface.
+
+      A sub-surface becomes mapped, when a non-NULL wl_buffer is applied
+      and the parent surface is mapped. The order of which one happens
+      first is irrelevant. A sub-surface is hidden if the parent becomes
+      hidden, or if a NULL wl_buffer is applied.
+
+      The behaviour of wl_surface.commit request on a sub-surface depends
+      on the commit mode, set by wl_subsurface.set_commit_mode. The commit
+      mode affects operations with the wl_surface state of sub-surfaces.
+
+      If the commit mode is "parent-cached", wl_surface.commit on a
+      sub-surface will accumulate the committed state in a cache,
+      but the state will not be applied and hence will not change the
+      compositor output. The cached state is applied to the sub-surface when
+      wl_surface.commit is called on the parent surface, after the parent
+      surface's own state is applied. This ensures atomic updates of the
+      parent and all its sub-surfaces with "parent-cached" commit mode.
+      Applying the cached state will invalidate the cache, so further
+      parent surface commits do not (re-)apply old state.
+
+      If the commit mode is "independent", wl_surface.commit on a
+      sub-surface will apply the pending state without caching.
+      Calling wl_surface.commit on the parent surface has no effect on the
+      sub-surface state. This mode allows a sub-surface to be updated
+      on its own.
+
+      Sub-surfaces have also other kind of state, which is managed by
+      wl_subsurface requests, as opposed to wl_surface requests. This
+      state includes the sub-surface position relative to the parent
+      surface (wl_subsurface.set_position), and the stacking order of
+      the parent and its sub-surfaces (wl_subsurface.place_above and
+      .place_below). This state is applied on the parent surface's
+      commit, regardless of commit mode. As the exception, changes to
+      commit mode are applied immediately.
+
+      The wl_subsurface object must be destroyed before the wl_surface object
+      it was create for. Note, that destroying either object
+      takes effect immediately. If you need to synchronize the removal
+      of a sub-surface to the parent surface update, unmap the sub-surface
+      first by attaching a NULL wl_buffer, update parent, and then destroy
+      the sub-surface.
+
+      If the parent wl_surface object is destroyed, the sub-surface is
+      unmapped.
+    </description>
+
+    <request name="destroy" type="destructor">
+      <description summary="remove sub-surface interface">
+	The sub-surface interface is removed from the wl_surface object
+	that was turned into a sub-surface with
+	wl_subcompositor.get_subsurface request. The wl_surface's association
+	to the parent is deleted, and the wl_surface loses its role as
+	a sub-surface. The wl_surface is unmapped.
+      </description>
+    </request>
+
+    <enum name="error">
+      <entry name="bad_surface" value="0"
+             summary="wl_surface is not a sibling or the parent"/>
+      <entry name="bad_value" value="1"
+             summary="unknown enum parameter value"/>
+    </enum>
+
+    <request name="set_position">
+      <description summary="reposition the sub-surface">
+	This schedules a sub-surface position change.
+	The sub-surface will be moved so, that its origin (top-left
+	corner pixel) will be at the location x, y of the parent surface.
+
+	The next wl_surface.commit on the parent surface will reset
+	the sub-surface's position to the scheduled coordinates.
+
+	The initial position is 0, 0.
+      </description>
+
+      <arg name="x" type="int" summary="coordinate in the parent surface"/>
+      <arg name="y" type="int" summary="coordinate in the parent surface"/>
+    </request>
+
+    <request name="place_above">
+      <description summary="restack the sub-surface">
+	This sub-surface is taken from the stack, and put back just
+	above the reference surface, changing the z-order of the sub-surfaces.
+	The reference surface must be one of the sibling surfaces, or the
+	parent surface. Using any other surface, including this sub-surface,
+	will cause a protocol error.
+
+	The z-order is double-buffered state, and will be applied on the
+	next commit of the parent surface.
+	See wl_surface.commit and wl_subcompositor.get_subsurface.
+      </description>
+
+      <arg name="sibling" type="object" interface="wl_surface"
+           summary="the reference surface"/>
+    </request>
+
+    <request name="place_below">
+      <description summary="restack the sub-surface">
+	The sub-surface is placed just below of the reference surface.
+	See wl_subsurface.place_above.
+      </description>
+
+      <arg name="sibling" type="object" interface="wl_surface"
+           summary="the reference surface"/>
+    </request>
+
+    <enum name="commit_mode">
+      <entry name="parent_cached" value="1"
+             summary="sub-surface commit only caches state"/>
+      <entry name="independent" value="2"
+             summary="sub-surface commit applies state"/>
+    </enum>
+
+    <request name="set_commit_mode">
+      <description summary="change sub-surface commit behaviour">
+	Change how parent and sub-surface commits apply the pending
+	surface state. This request is effective immediately.
+	See the wl_subsurface description.
+
+	The default commit mode is parent-cached.
+      </description>
+
+      <arg name="mode" type="uint" summary="enum commit_mode"/>
+    </request>
+
+  </interface>
+</protocol>
diff --git a/src/.gitignore b/src/.gitignore
index 3c27953..c1392e1 100644
--- a/src/.gitignore
+++ b/src/.gitignore
@@ -17,3 +17,6 @@ workspaces-protocol.c
 workspaces-server-protocol.h
 input-method-protocol.c
 input-method-server-protocol.h
+subsurface-server-protocol.h
+subsurface-protocol.c
+
diff --git a/src/Makefile.am b/src/Makefile.am
index 2c93a7b..bcc8795 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -34,6 +34,8 @@ weston_SOURCES =				\
 	input-method-server-protocol.h		\
 	workspaces-protocol.c			\
 	workspaces-server-protocol.h		\
+	subsurface-protocol.c			\
+	subsurface-server-protocol.h		\
 	bindings.c				\
 	animation.c				\
 	gl-renderer.h				\
@@ -252,6 +254,8 @@ BUILT_SOURCES =					\
 	input-method-server-protocol.h		\
 	workspaces-server-protocol.h		\
 	workspaces-protocol.c			\
+	subsurface-server-protocol.h		\
+	subsurface-protocol.c			\
 	git-version.h
 
 CLEANFILES = $(BUILT_SOURCES)
diff --git a/src/compositor.h b/src/compositor.h
index cd21c32..3d197ef 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -31,6 +31,7 @@
 #include "version.h"
 #include "matrix.h"
 #include "config-parser.h"
+#include "subsurface-server-protocol.h"
 
 #define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
 
diff --git a/tests/.gitignore b/tests/.gitignore
index 05bc024..fa19888 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -11,3 +11,5 @@ keyboard-test
 event-test
 button-test
 xwayland-test
+subsurface-client-protocol.h
+subsurface-protocol.c
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 0f81458..9b9351a 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -60,6 +60,8 @@ weston_test_client_src =		\
 	weston-test-client-helper.h	\
 	wayland-test-protocol.c		\
 	wayland-test-client-protocol.h	\
+	subsurface-protocol.c		\
+	subsurface-client-protocol.h	\
 	$(weston_test_runner_src)
 weston_test_client_libs =		\
 	$(SIMPLE_CLIENT_LIBS)		\
@@ -109,6 +111,8 @@ endif
 EXTRA_DIST = weston-tests-env
 
 BUILT_SOURCES =					\
+	subsurface-protocol.c			\
+	subsurface-client-protocol.h		\
 	wayland-test-protocol.c			\
 	wayland-test-server-protocol.h		\
 	wayland-test-client-protocol.h
-- 
1.7.12.4



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